IP Multimedia Subsystem IMS is the core technology of next generation networks can provide real-time IP multimedia services and VoIP services through IMS, but IMS is not perfect, of which there are still some problems. IMS in real-time business a higher demand for mobility support, voice and video data usually use real-time transport protocol RTP to transfer user data protocol over UDP, requiring low transmission delay, seamless switching, as well as higher bandwidth utilization. In this paper, the IMS-related issues, the IMS network protocol.The SIP protocol simulation. Simulation results show that more of the nodes, the network send and receive packets faster, the results of this paper is the study of the IMS network, the actual reference value